Is Jenova an Ancient?

The game says the Cetra/ancients are born on Earth. Jenova is referred to as an Ancient.

Is Jenova a Cetra?

As Jenova was not a Cetra, Shinra was, understandably, unsuccessful in using its cells to create a Cetra hybrid; however those humans treated with its cells proved to be super-soldiers, leading to Shinra's injection of Jenova cells into the members of its elite military force, SOLDIER.

Is Sephiroth actually Jenova?

At different parts of the game, Sephiroth refers to Jenova as his mother. ... Through a series of strange decisions, Lucrecia ended up with Hojo and she gave birth to Sephiroth, who was injected with Jenova's cells while still in the womb. While Jenova is not Sephiroth's mother, it did have an impact on who he became.